Re: [PATCH v3 1/4] mm/page_isolation: make page isolation a standalone bit.

Zi Yan
2025-05-09T13:57:53Z

On 8 May 2025, at 16:22, Zi Yan wrote:

> On 7 May 2025, at 17:10, Zi Yan wrote:
>
>> During page isolation, the original migratetype is overwritten, since
>> MIGRATE_* are enums and stored in pageblock bitmaps. Change
>> MIGRATE_ISOLATE to be stored a standalone bit, PB_migrate_isolate, like
>> PB_migrate_skip, so that migratetype is not lost during pageblock
>> isolation. pageblock bits needs to be word aligned, so expand
>> the number of pageblock bits from 4 to 8 and make PB_migrate_isolate bit 7.
>>
>> Signed-off-by: Zi Yan <ziy@nvidia.com>
>> ---
>> include/linux/mmzone.h | 17 ++++++++++----
>> include/linux/page-isolation.h | 2 +-
>> include/linux/pageblock-flags.h | 33 +++++++++++++++++++++++++-
>> mm/page_alloc.c | 41 ++++++++++++++++++++++++++++++++-
>> 4 files changed, 86 insertions(+), 7 deletions(-)
>>
>
> Here is the fixup 1/3 to address Johannes’ comments.
>
> From 7eb1d9fa58fdab216862436181e5d2baf2958c54 Mon Sep 17 00:00:00 2001
> From: Zi Yan <ziy@nvidia.com>
> Date: Thu, 8 May 2025 12:05:59 -0400
> Subject: [PATCH] fixup for mm/page_isolation: make page isolation a standalone
> bit
>
> 1. keep the original is_migrate_isolate_page()
> 2. move {get,set,clear}_pageblock_isolate() to mm/page_isolation.c
> 3. use a single version for get_pageblock_migratetype() and
> get_pfnblock_migratetype().
>
> Signed-off-by: Zi Yan <ziy@nvidia.com>
> ---
> include/linux/mmzone.h | 6 ------
> include/linux/page-isolation.h | 2 +-
> include/linux/pageblock-flags.h | 24 ------------------------
> mm/page_alloc.c | 25 ++++++++++---------------
> mm/page_isolation.c | 17 +++++++++++++++++
> 5 files changed, 28 insertions(+), 46 deletions(-)
>

Hi Andrew,

This fixup gets rid of the unused function warning[1].

BTW, this series gets several fixups. Let me know if you think a V4
is necessary. Thanks.

[1] https://lore.kernel.org/linux-mm/202505092126.yRGhLhg1-lkp@intel.com/

From 126d116cb737bf3d8c475460b9b48edc6696e6dc Mon Sep 17 00:00:00 2001
From: Zi Yan <ziy@nvidia.com>
Date: Fri, 9 May 2025 09:29:09 -0400
Subject: [PATCH] fix unused function warnings

1. add __maybe_unused to get_pageblock_isolate(), which is used in
VM_BUG_ON only.
2. remove unused set_pageblock_isolate().

Signed-off-by: Zi Yan <ziy@nvidia.com>
---
mm/page_isolation.c | 8 +-------
1 file changed, 1 insertion(+), 7 deletions(-)

diff --git a/mm/page_isolation.c b/mm/page_isolation.c
index b0f83a7c508d..ce7e38c9f839 100644
--- a/mm/page_isolation.c
+++ b/mm/page_isolation.c
@@ -15,7 +15,7 @@
#define CREATE_TRACE_POINTS
#include <trace/events/page_isolation.h>

-static inline bool get_pageblock_isolate(struct page *page)
+static inline bool __maybe_unused get_pageblock_isolate(struct page *page)
{
return get_pfnblock_flags_mask(page, page_to_pfn(page),
PB_migrate_isolate_bit);
@@ -25,12 +25,6 @@ static inline void clear_pageblock_isolate(struct page *page)
set_pfnblock_flags_mask(page, 0, page_to_pfn(page),
PB_migrate_isolate_bit);
}
-static inline void set_pageblock_isolate(struct page *page)
-{
- set_pfnblock_flags_mask(page, PB_migrate_isolate_bit,
- page_to_pfn(page),
- PB_migrate_isolate_bit);
-}

/*
* This function checks whether the range [start_pfn, end_pfn) includes
--
2.47.2

--
Best Regards,
Yan, Zi